API Test Suite Builder

What it does

Detects API endpoints in your source tree, expands each one into a matrix of required test cases, and emits ready-to-run test files.

• Route detection: Next.js App Router (app/api/**/route.ts), Express (router.get/post...), FastAPI (@router.get), Django REST (urlpatterns, router.register)
• Auth matrix: missing header (401), malformed token (401), wrong role (403), expired JWT (401), token from a deleted user (401)
• Input validation matrix: empty body, missing required fields one at a time, wrong types, boundary values (min-1 / min / max / max+1), SQL injection and XSS payloads, nulls
• Error-code coverage: 400/401/403/404/422/500 per route
• Extras: pagination (first/last/empty/oversized), file uploads (valid, oversized, wrong MIME, empty), rate limiting (burst, per-user vs global)
• Output: Vitest + Supertest for Node, Pytest + httpx for Python

It also ships an opinionated list of pitfalls (happy-path-only tests, hardcoded IDs, shared state) and best practices (one describe per endpoint, assert that secrets never leak, run rate-limit tests last).

Who it's for

• Backend developers inheriting a legacy API with zero test coverage
• Teams practising TDD who want a test scaffold before implementation
• QA and platform engineers preparing pre-release regression or security audits
• Anyone running Next.js API Routes, Express, FastAPI, or Django REST Framework

Example uses

1. Baseline an untested Express service — "Scan every route under src and generate Vitest+Supertest smoke tests." You get a route map plus per-endpoint describe blocks with 401/404 cases wired in.
2. Security-audit prep for a payments API — "Write tests for POST /api/payments applying the full auth and validation matrix." Expired tokens, cross-tenant 403s, amount boundary values and injection payloads all come out at once.
3. TDD a new FastAPI feature — Before writing code, ask it to read the router file and produce a Pytest+httpx scaffold with response-shape assertions and pagination boundary tests so you start from red.

Install the skill I found on Claude Skill Mart.
Copy the .gemini/skills/api-test-suite-builder folder from the GitHub repo alirezarezvani/claude-skills into my ~/.claude/skills/api-test-suite-builder/.
When it's done, tell me in one line what this skill can do.